1. Field of the Invention
The present invention generally relates to a method for manufacturing patterned thin-film layer on a substrate.
2. Description of Related Art
At present, methods for manufacturing a patterned thin-film layer on a substrate include a photolithographic method and an ink-jet method.
The photolithographic method is described as below: applying a photoresist layer on a substrate; exposing the photoresist layer using a photo mask with a predetermined pattern and developing the exposed photoresist layer using the conventional method to form a predetermined patterned thin-film layer. Disadvantage of the conventional photolithographic method is that a large part of the photoresist material is wasted thus, the efficiency is lowered.
Referring to FIG. 7, the ink-jet method includes following steps: referring to FIG. 7(a), a substrate 42 with a plurality of banks 44 thereon is provided, wherein the plurality of banks 44 defining a plurality of spaces 46 therein; the surfaces of the banks 44 is irradiated by ultraviolet (UV for short hereinafter) light beams 48 perpendicular to the top surface of the banks 44. Referring to FIGS. 7(b) and 7(c), ink 54 is deposited into the spaces 46 by a nozzle 52. A patterned thin-film layer (not shown) is formed after the ink 54 being cured.
In the ink-jet method, ink with an appropriate viscosity and a surface tension is necessary (see “the Fluid Property Dependency on Ink Jetting Characteristics”, Proceedings of the 2005 IEEE, pp. 258-260, 2005.11). Therefore, ink applied to the ink-jet method must have a certain level of viscosity and a certain level of surface tension in order to increase surface wettability of the ink on the substrate 42 and the banks 44. Alternatively, a method of irradiating the substrate 42 and the banks 44 with UV light, as shown in FIG. 7(a), is being applied to increase surface wettability of the ink on the substrate 42 and the banks 44.
In FIG. 7(a), the UV light beams 48 can decompose non-hydrophile substance, and thus increase the surface wettability of the top surfaces of the banks 44. If a material of the banks 44 is an organic material, the UV light beams 48 also can break the unsaturated links of the organic material adjacent of the outer surface of the banks 44. This will further increase the surface wettability of the top surface of the banks 44. In FIG. 7(c), the UV light beams perpendicularly irradiate the top surfaces of banks 44, which have better surface wettability than the side surfaces of banks 44. Therefore, when an ink 542 deposited in the space 46 overflows to the top surface of the bank 44, the ink 542 is prone to flowing along the top surfaces of the bank 44 and is mixed with an ink 544 adjacent to the ink 542. This may reduce purity of the ink in the same space.
What is needed, therefore, is a method for manufacturing a patterned thin-film layers with high purity of the ink in the same space.